i slept with my boyfriend on july 26 and now its the aug.18th and my period should have been here on the aug. 8...whch makes me 10 days late of my period and i dont have any signs that my menstruation is about to arrive...normally i can be 2 days late but not so much..i took a blood pregnancy test and it turned out negative..but i feel like my breast are bigger and very very nauseaus!! i suffer from anxiety which could be affecting me..my question is could these blood test fail if i onle have two weeks or so pregnant??? Should i take another test to be positive or go to a ginecologist?